Depends on what screen size/resolution you favour, and the type of keyboard.

I like the older keyboards and I'm ok with 1366x768 so I'm happy with an X220 with 8Gb RAM and a 256Gb ssd (sata). I know many people would find that unacceptable.

I can get a monitor if needed, it's more meant to be a luggable. I'm not a keyboard purist -- I hunt and peck :-)